Continuous-Flow PEALD System Plasma Isolation
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Solution Overview
Problem
Traditional atomic layer deposition (ALD) systems face challenges in producing extremely uniform films across substrates with short cycle-times, as high energy plasma flux damages the substrate and deteriorates film quality, and existing designs fail to achieve the required high quality, uniformity, low cost, and high throughput for industrial applications.
Innovation Solution
The continuous-flow plasma enhanced atomic layer deposition (PEALD) system uses a planar inductively coupled plasma source with a grounded metal plate and ceramic plate to isolate the plasma from the substrate, allowing only excited neutrals to reach the substrate, preventing damaging plasma flux and eliminating the need for ammonia for nitridation, thereby achieving uniform film deposition with reduced cycle-times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high energy plasma flux is used to activate reactants in PEALD, then reactant activation is improved, but substrate damage and film quality deterioration occur
Solution Approach 1:
The reactor is divided into two distinct zones: a plasma generation zone and a substrate deposition zone. The plasma is generated in one zone and then transported to the substrate zone, separating the high-energy plasma generation from the substrate exposure, thereby activating reactants without damaging the substrate.
Solution Approach 2:
A carrier gas flow acts as an intermediary to transport activated reactant species from the plasma zone to the substrate zone. This intermediary medium allows the transfer of activated species while filtering out harmful high-energy plasma components that would damage the substrate.
2Reliability
If traditional pulsed ALD cycles with purge steps are used, then excess reactant removal is achieved, but cycle-time is extended
Solution Approach 1:
The system employs continuous flow of reactants through the reactor rather than traditional pulsed cycles with purge steps. The continuous flow regime maintains constant reactant supply and automatic excess reactant removal, eliminating idle purge time while ensuring complete reactant consumption and maintaining deposition reliability.
Solution Approach 2:
The system uses periodic modulation of reactant flow rates or plasma power to control the deposition process, replacing the traditional periodic pulse-purge cycle with a continuous flow regime that has periodic control adjustments, thereby reducing cycle time while maintaining film quality.
3Quantity of substance
If ammonia is used for nitridation in PEALD, then nitride film deposition is achieved, but expensive abatement processes are required
Solution Approach 1:
The system changes the chemical parameters of the reactants by using alternative nitrogen-containing precursors or plasma chemistry approaches that do not require ammonia. This parameter change in the reactant composition eliminates the need for expensive ammonia abatement processes while achieving the same nitride film deposition objective.
Solution Approach 2:
The system uses alternative precursors or in-situ generated nitrogen species that are either non-harmful or easily removable, replacing ammonia with substances that do not require costly abatement infrastructure, thereby reducing operational costs while maintaining film deposition capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in remarkably uniform, high-quality films with little or no hydrogen content, significantly reducing cycle-times and operational costs, while avoiding substrate damage and the need for expensive ammonia abatement processes.
Implementation Method 1
a planar inductively coupled plasma source
Implementation Method 2
Gas A is flowed to the planar inductively coupled plasma source substantially vertically with respect to the substrate, and the plasma from the plasma gas is continuously generated in the chamber below a quartz plate of the plasma source
Implementation Method 3
The plasma from the plasma gas is continuously generated in the chamber below a quartz plate of the plasma source. The quartz plate, a grounded metal plate, and a ceramic plate, each having a number of holes, are affixed in the chamber between the plasma source and the substrate such that each hole of one plate is perfectly aligned with a corresponding hole of the other plates
Implementation Method 4
The excited neutrals, the pulse of gas B and the heated substrate react in a self-limiting manner to deposit an atomically sized film on the substrate surface
Data Source
AI summary
Techniques are disclosed for methods and apparatuses for performing continuous-flow plasma enhanced atomic layer deposition (PEALD). Plasma gas, containing one or more component gases, is continuously flowed to a planar inductive coupled plasma source attached at an upper end of a cylindrical chamber. Plasma is separated from the ALD volume surrounding a wafer/substrate in the lower end of the chamber by a combination of a grounded metal plate and a ceramic plate. Each plate has a number of mutually aligned holes. The ceramic plate has holes with a diameter less than 2 Debye lengths and has a large aspect ratio. This prevents damaging plasma flux from entering the ALD volume into which a gaseous metal precursor is also pulsed. The self-limiting ALD reaction involving the heated substrate, the excited neutrals from the plasma gas, and the metal precursor produce an ultra-uniform, high quality film on the wafer. A batch configuration to simultaneously coat multiple wafers is also disclosed.